Hydrogenation reactions are often hampered by a limited availability of hydrogen that must be transferred to the liquid phase before the reaction can start, and by the use of a low hydrogen partial pressure. Hydrogenation reactions may be favored by the use of hydrogen donors, compounds such as naphthalene that are reversibly hydrogenated-dehydrogenated in the reacting mixture. In this way, when using hydrogen donors in a particular hydrogenation reaction, the hydrogenation-dehydrogenation equilibrium of the hydrogen donor generates an additional amount of hydrogen atoms in the reaction environment, thus favoring the desired hydrogenation reaction.
A typical hydrogen donor is decalin (decahydronaphthalene), which in a hydrogenation reaction is in equilibrium with tetralin (1,2,3,4-tetrahydronaphthalene) and naphthalene. It must be pointed out that in the case of naphthalene, tetralin and decalin, their separation and recovery from the reaction mixture is usually difficult due to their high solubilities in the reactants, products and solvents.

U.S. Pat. No. 3,413,212 discloses a process for upgrading the properties of hydrocarbon cuts having boiling points above 204° C. using a crystalline aluminosilicate catalyst and a hydrogen donor at temperatures in the 290-593° C. range with the aim of obtaining hydrocarbon fractions in the gasoline range. The hydrogen donor is prepared by partial hydrogenation of polynuclear aromatic compounds, and is preferably 1,2,3,4-tetrahydronaphthalene and decahydronaphthalene, following a mechanism of hydrogen transfer in the presence of the catalytic material.
U.S. Pat. No. 4,642,175 discloses the reduction of coke formation of heavy hydrocarbons by treatment with transition metals naphtenates at temperatures below 350° C. The product is stable and can be fed to subsequent processes such as catalytic and thermal cracking, including visbreaking and coking, with an improvement in liquid yields and lower coke formation.
U.S. Pat. No. 4,049,536 discloses a process for coal liquefaction to produce liquid hydrocarbons by means of the following stages: a) the coal is mixed with a non-hydrogen donor solvent and an orto-quinone compound to form a coal-in-liquid suspension, and b) the suspension is mixed with molecular hydrogen at a pressure and temperature adequate for coal hydroconversion and liquefaction. Orto-quinone acts as a hydrogenation catalyst, promoting coal hydrogenation in the liquefaction zone in the presence of molecular hydrogen without a hydrogen donor solvent.
U.S. Patent No. 20110172461 discloses a methodology for the recycling of a polymeric material that comprises a depolymerization of the material by heating in the presence of a hydrogen donor and a strong base. This method was developed for the recycling of polyethylene terephthalate via depolymerization by heating in the presence of a hydrogen donor and a strong base.
U.S. Pat. No. 4,395,324 discloses the use of a low-boiling-point hydrogen donor such as tetralin in a cracking process.
U.S. Pat. No. 4,696,733 discloses a process for the partial hydrogenation of polynuclear aromatic compounds using a manganese catalyst in the presence of hydrogen at high temperature. The resulting partially hydrogenated products are used as hydrogen donors in the thermal cracking process.
U.S. Pat. No. 5,399,632 discloses the hydrogenation of unsaturated copolymers, without the addition of hydrogen, using a hydrogen donor in the presence of a Group VII metal catalyst, more specifically a supported palladium catalyst.
U.S. Pat. No. 4,210,518 discloses improvement in liquid product yield obtained during coal or coke liquefaction using a hydrogen donor.
U.S. Pat. No. 4,345,989 discloses the conversion of coal to low-molecular-weight liquid hydrocarbons using a hydrogen donor solvent in the presence of an alkaline metal catalyst prepared by heating at a temperature above 800° F. in a reaction zone external to the liquefaction zone.
U.S. Pat. No. 4,485,004 discloses a process for the conversion of heavy hydrocarbons to lighter products by hydrocracking in the presence of a hydrogen donor having a boiling point above 200° C. and a hydrogenation catalyst made of cobalt, molybdenum, nickel, tungsten or a mixture of these.
U.S. Pat. No. 7,576,240 discloses the selective hydrogenation of double or triple bonds in organic molecules using a hydrogen donor.
U.S. Pat. No. 7,594,990 discloses a process where a hydrogen donor solvent is used to increase the residuals conversion in the ebullated bed residuals hydrocracking process. The hydrogen donor solvent is produced by means of hydroreforming reactions in the residuals hydrocracking. In this process the hydrogen donor solvent reduces the coke formation at the high operating temperatures.
U.S. Pat. No. 4,298,450 discloses a method for coal hydroconversion by treatment with a solvent at high temperatures and pressures, where an alcohol that contains a a-hydrogen atom, more specifically a secondary alcohol such as isopropanol is used as a hydrogen donor solvent.
U.S. Pat. No. 4,077,867 discloses a process for the catalytic hydroconversion of coal using a metallic compound and a hydrogen donor solvent in the presence of hydrogen. The preferred metallic compounds are made of molybdenum.
As disclosed in the aforementioned patents, liquid hydrogen donors such as tetralin or decalin may be well known; however, these compounds are expensive and their recovery and reuse is difficult; for these reasons, in certain embodiments of the present disclosure, we present heterogeneous hydrogen transfer agents, solids at reaction temperatures, which are constituted by polymers prepared from monomers that have a naphthalene type unit in order to participate in reduction reactions. The hydrogen transfer agents, as disclosed in various embodiments of the present disclosure, have fusion or decomposition temperatures above the required reaction temperature, in the range of 100 to 450° C., are chemically stable at the reaction conditions and have textural properties suitable for industrial application.
BET surface areaTotal pore volumeAverage poreSample(m2/g)(cm3/g)diameter (Å)Polymer 11.56880.004818122.8340Polymer 1135.23120.22020248.6196extruded insilica
It is therefore an advantage of the present disclosure to apply these polymers and copolymers as hydrogen transfer agents to carry out hydrogenation reactions and in general any chemical reaction involving a reduction.
Another advantage of this disclosure is that the application of these heterogeneous hydrogen transfer agents in hydrogenation reactions and chemical reduction reactions is carried out in the presence of reducing agents such as hydrogen. This disclosure is an alternative for executing any reaction that involves the reduction of double bonds using heterogeneous hydrogen donors based upon naphthalene-type compounds that can be reversibly hydrogenated-dehydrogenated in the reaction mixture.
This disclosure is an alternative for executing any reaction that involves the reduction of double bonds using heterogeneous hydrogen donors based upon naphthalene-type compounds that can be reversibly hydrogenated-dehydrogenated in the reaction mixture.